Project template
Your preparation checklist
Use it as a working list. The final submission still needs to match your actual scope and the City’s current requirements.
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What to do next
- Confirm this is a basement second unit in an existing building
- Review the City’s 2024 OBC guide
- Prepare the complete permit drawings
- Submit before construction
Official sources behind this page
Dwelling unit / apartmentPermit required
Oshawa lists adding a dwelling unit or apartment among projects requiring a building permit.
City of OshawaBuilding Permits · Residential permit triggers and project resources
2026-10-01Open proof
Basement secondary suiteDedicated 2024 OBC guidance
Oshawa publishes a current guide for basement secondary suites in existing buildings.
City of OshawaOntario Building Code Guide to Basement Secondary Suite · Basement secondary-suite Building Code guidance
2026-10-01Open proof
Project scopeDetached accessory units / third units use different requirements
The City guide states that its basement-secondary-suite content does not apply to an accessory-building dwelling unit or addition of a third unit.
City of OshawaOntario Building Code Guide to Basement Secondary Suite · Basement secondary-suite Building Code guidance
2026-10-01Open proof
Need the full project answer?
The main guide keeps the permit trigger, zoning questions, documents, fees, timing and next steps together.
Open the basement secondary suite guide